The Frequent Hemodialysis Network (FHN) Study is a randomized clinical trial designed to test hypotheses related to the feasibility, safety, and efficacy of frequent (6x per week) vs. conventional (3x per week) hemodialysis. The recently completed NIDDK-funded MEMO Study demonstrated that survival and many other outcomes were not appreciably influenced by significant increases in equilibrated Kt/Vurea, a parameter of dialysis dose, when hemodialysis was given thrice weekly. Clinical experience and published anecdotal reports suggest that more frequent dialysis may result in reduced frequency and duration of hospitalization, improved control of volume overload, hypertension and anemia, correction of disorders of mineral metabolism, and enhanced quality of life. Given the high mortality rates and significant morbidity associated with end-stage renal disease, a rigorous evaluation of alternative dialysis strategies is warranted. The Investigators have constructed a consortium of University- and community-based nephrologists and dialysis units throughout the state of California - the California Coordinating Clinical Center (CCC). We serve urban and suburban communities with extensive racial, ethnic and socioeconomic diversity. We intend on enrolling 125 subjects (adults and children) as requested by the RFA. Subject recruitment, retention and adherence have been excellent;plans are in place to augment recruitment at existing sites by approaching additional local dialysis facilities and to expand recruitment to VA medical centers affiliated with participating universities. The sample size will not be sufficient to demonstrate a difference in survival among groups. Safety and clinical events (e.g., hospitalization) will continue to be carefully tracked. With continued enrollment and randomization, the study should have sufficient power to detect clinically meaningful differences in the co-primary outcomes (the composite of mortality and change in left ventricular mass;and the composite of mortality and change in the Physical Health Composite of the SF-36). The study should also have sufficient power to detect clinically meaningful differences in other secondary outcomes. Dr. Chertow and his colleages have assembled a talented group of investigators and coordinators. The consortium has worked effectively with multiple industry partners. We are collectively committed to working cooperatively and constructively with the other CCC and DCC to reach all FHN study goals.